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/*-
* Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/netinet/ipfw/ip_fw_dynamic.c 236692 2012-06-06 18:00:19Z oleg $");
#define DEB(x)
#define DDB(x) x
/*
* Dynamic rule support for ipfw
*/
#include "opt_ipfw.h"
#include "opt_inet.h"
#ifndef INET
#error IPFIREWALL requires INET.
#endif /* INET */
#include "opt_inet6.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <net/ethernet.h> /* for ETHERTYPE_IP */
#include <net/if.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h> /* ip_defttl */
#include <netinet/ip_fw.h>
#include <netinet/ipfw/ip_fw_private.h>
#include <netinet/tcp_var.h>
#include <netinet/udp.h>
#include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */
#ifdef INET6
#include <netinet6/in6_var.h>
#include <netinet6/ip6_var.h>
#endif
#include <machine/in_cksum.h> /* XXX for in_cksum */
#ifdef MAC
#include <security/mac/mac_framework.h>
#endif
/*
* Description of dynamic rules.
*
* Dynamic rules are stored in lists accessed through a hash table
* (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
* be modified through the sysctl variable dyn_buckets which is
* updated when the table becomes empty.
*
* XXX currently there is only one list, ipfw_dyn.
*
* When a packet is received, its address fields are first masked
* with the mask defined for the rule, then hashed, then matched
* against the entries in the corresponding list.
* Dynamic rules can be used for different purposes:
* + stateful rules;
* + enforcing limits on the number of sessions;
* + in-kernel NAT (not implemented yet)
*
* The lifetime of dynamic rules is regulated by dyn_*_lifetime,
* measured in seconds and depending on the flags.
*
* The total number of dynamic rules is stored in dyn_count.
* The max number of dynamic rules is dyn_max. When we reach
* the maximum number of rules we do not create anymore. This is
* done to avoid consuming too much memory, but also too much
* time when searching on each packet (ideally, we should try instead
* to put a limit on the length of the list on each bucket...).
*
* Each dynamic rule holds a pointer to the parent ipfw rule so
* we know what action to perform. Dynamic rules are removed when
* the parent rule is deleted. XXX we should make them survive.
*
* There are some limitations with dynamic rules -- we do not
* obey the 'randomized match', and we do not do multiple
* passes through the firewall. XXX check the latter!!!
*/
/*
* Static variables followed by global ones
*/
static VNET_DEFINE(ipfw_dyn_rule **, ipfw_dyn_v);
static VNET_DEFINE(u_int32_t, dyn_buckets);
static VNET_DEFINE(u_int32_t, curr_dyn_buckets);
static VNET_DEFINE(struct callout, ipfw_timeout);
#define V_ipfw_dyn_v VNET(ipfw_dyn_v)
#define V_dyn_buckets VNET(dyn_buckets)
#define V_curr_dyn_buckets VNET(curr_dyn_buckets)
#define V_ipfw_timeout VNET(ipfw_timeout)
static uma_zone_t ipfw_dyn_rule_zone;
#ifndef __FreeBSD__
DEFINE_SPINLOCK(ipfw_dyn_mtx);
#else
static struct mtx ipfw_dyn_mtx; /* mutex guarding dynamic rules */
#endif
#define IPFW_DYN_LOCK_INIT() \
mtx_init(&ipfw_dyn_mtx, "IPFW dynamic rules", NULL, MTX_DEF)
#define IPFW_DYN_LOCK_DESTROY() mtx_destroy(&ipfw_dyn_mtx)
#define IPFW_DYN_LOCK() mtx_lock(&ipfw_dyn_mtx)
#define IPFW_DYN_UNLOCK() mtx_unlock(&ipfw_dyn_mtx)
#define IPFW_DYN_LOCK_ASSERT() mtx_assert(&ipfw_dyn_mtx, MA_OWNED)
void
ipfw_dyn_unlock(void)
{
IPFW_DYN_UNLOCK();
}
/*
* Timeouts for various events in handing dynamic rules.
*/
static VNET_DEFINE(u_int32_t, dyn_ack_lifetime);
static VNET_DEFINE(u_int32_t, dyn_syn_lifetime);
static VNET_DEFINE(u_int32_t, dyn_fin_lifetime);
static VNET_DEFINE(u_int32_t, dyn_rst_lifetime);
static VNET_DEFINE(u_int32_t, dyn_udp_lifetime);
static VNET_DEFINE(u_int32_t, dyn_short_lifetime);
#define V_dyn_ack_lifetime VNET(dyn_ack_lifetime)
#define V_dyn_syn_lifetime VNET(dyn_syn_lifetime)
#define V_dyn_fin_lifetime VNET(dyn_fin_lifetime)
#define V_dyn_rst_lifetime VNET(dyn_rst_lifetime)
#define V_dyn_udp_lifetime VNET(dyn_udp_lifetime)
#define V_dyn_short_lifetime VNET(dyn_short_lifetime)
/*
* Keepalives are sent if dyn_keepalive is set. They are sent every
* dyn_keepalive_period seconds, in the last dyn_keepalive_interval
* seconds of lifetime of a rule.
* dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
* than dyn_keepalive_period.
*/
static VNET_DEFINE(u_int32_t, dyn_keepalive_interval);
static VNET_DEFINE(u_int32_t, dyn_keepalive_period);
static VNET_DEFINE(u_int32_t, dyn_keepalive);
#define V_dyn_keepalive_interval VNET(dyn_keepalive_interval)
#define V_dyn_keepalive_period VNET(dyn_keepalive_period)
#define V_dyn_keepalive VNET(dyn_keepalive)
static VNET_DEFINE(u_int32_t, dyn_count); /* # of dynamic rules */
static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */
#define V_dyn_count VNET(dyn_count)
#define V_dyn_max VNET(dyn_max)
#ifdef SYSCTL_NODE
SYSBEGIN(f2)
SYSCTL_DECL(_net_inet_ip_fw);
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets,
CTLFLAG_RW, &VNET_NAME(dyn_buckets), 0,
"Number of dyn. buckets");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets,
CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0,
"Current Number of dyn. buckets");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_count,
CTLFLAG_RD, &VNET_NAME(dyn_count), 0,
"Number of dyn. rules");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_max,
CTLFLAG_RW, &VNET_NAME(dyn_max), 0,
"Max number of dyn. rules");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime,
CTLFLAG_RW, &VNET_NAME(dyn_ack_lifetime), 0,
"Lifetime of dyn. rules for acks");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime,
CTLFLAG_RW, &VNET_NAME(dyn_syn_lifetime), 0,
"Lifetime of dyn. rules for syn");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime,
CTLFLAG_RW, &VNET_NAME(dyn_fin_lifetime), 0,
"Lifetime of dyn. rules for fin");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime,
CTLFLAG_RW, &VNET_NAME(dyn_rst_lifetime), 0,
"Lifetime of dyn. rules for rst");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime,
CTLFLAG_RW, &VNET_NAME(dyn_udp_lifetime), 0,
"Lifetime of dyn. rules for UDP");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime,
CTLFLAG_RW, &VNET_NAME(dyn_short_lifetime), 0,
"Lifetime of dyn. rules for other situations");
SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive,
CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0,
"Enable keepalives for dyn. rules");
SYSEND
#endif /* SYSCTL_NODE */
static __inline int
hash_packet6(struct ipfw_flow_id *id)
{
u_int32_t i;
i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^
(id->dst_ip6.__u6_addr.__u6_addr32[3]) ^
(id->src_ip6.__u6_addr.__u6_addr32[2]) ^
(id->src_ip6.__u6_addr.__u6_addr32[3]) ^
(id->dst_port) ^ (id->src_port);
return i;
}
/*
* IMPORTANT: the hash function for dynamic rules must be commutative
* in source and destination (ip,port), because rules are bidirectional
* and we want to find both in the same bucket.
*/
static __inline int
hash_packet(struct ipfw_flow_id *id)
{
u_int32_t i;
#ifdef INET6
if (IS_IP6_FLOW_ID(id))
i = hash_packet6(id);
else
#endif /* INET6 */
i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
i &= (V_curr_dyn_buckets - 1);
return i;
}
static __inline void
unlink_dyn_rule_print(struct ipfw_flow_id *id)
{
struct in_addr da;
#ifdef INET6
char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
#else
char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
#endif
#ifdef INET6
if (IS_IP6_FLOW_ID(id)) {
ip6_sprintf(src, &id->src_ip6);
ip6_sprintf(dst, &id->dst_ip6);
} else
#endif
{
da.s_addr = htonl(id->src_ip);
inet_ntoa_r(da, src);
da.s_addr = htonl(id->dst_ip);
inet_ntoa_r(da, dst);
}
printf("ipfw: unlink entry %s %d -> %s %d, %d left\n",
src, id->src_port, dst, id->dst_port, V_dyn_count - 1);
}
/**
* unlink a dynamic rule from a chain. prev is a pointer to
* the previous one, q is a pointer to the rule to delete,
* head is a pointer to the head of the queue.
* Modifies q and potentially also head.
*/
#define UNLINK_DYN_RULE(prev, head, q) { \
ipfw_dyn_rule *old_q = q; \
\
/* remove a refcount to the parent */ \
if (q->dyn_type == O_LIMIT) \
q->parent->count--; \
DEB(unlink_dyn_rule_print(&q->id);) \
if (prev != NULL) \
prev->next = q = q->next; \
else \
head = q = q->next; \
V_dyn_count--; \
uma_zfree(ipfw_dyn_rule_zone, old_q); }
#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0)
/**
* Remove dynamic rules pointing to "rule", or all of them if rule == NULL.
*
* If keep_me == NULL, rules are deleted even if not expired,
* otherwise only expired rules are removed.
*
* The value of the second parameter is also used to point to identify
* a rule we absolutely do not want to remove (e.g. because we are
* holding a reference to it -- this is the case with O_LIMIT_PARENT
* rules). The pointer is only used for comparison, so any non-null
* value will do.
*/
static void
remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me)
{
static u_int32_t last_remove = 0;
#define FORCE (keep_me == NULL)
ipfw_dyn_rule *prev, *q;
int i, pass = 0, max_pass = 0;
IPFW_DYN_LOCK_ASSERT();
if (V_ipfw_dyn_v == NULL || V_dyn_count == 0)
return;
/* do not expire more than once per second, it is useless */
if (!FORCE && last_remove == time_uptime)
return;
last_remove = time_uptime;
/*
* because O_LIMIT refer to parent rules, during the first pass only
* remove child and mark any pending LIMIT_PARENT, and remove
* them in a second pass.
*/
next_pass:
for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
for (prev=NULL, q = V_ipfw_dyn_v[i] ; q ; ) {
/*
* Logic can become complex here, so we split tests.
*/
if (q == keep_me)
goto next;
if (rule != NULL && rule != q->rule)
goto next; /* not the one we are looking for */
if (q->dyn_type == O_LIMIT_PARENT) {
/*
* handle parent in the second pass,
* record we need one.
*/
max_pass = 1;
if (pass == 0)
goto next;
if (FORCE && q->count != 0 ) {
/* XXX should not happen! */
printf("ipfw: OUCH! cannot remove rule,"
" count %d\n", q->count);
}
} else {
if (!FORCE &&
!TIME_LEQ( q->expire, time_uptime ))
goto next;
}
if (q->dyn_type != O_LIMIT_PARENT || !q->count) {
UNLINK_DYN_RULE(prev, V_ipfw_dyn_v[i], q);
continue;
}
next:
prev=q;
q=q->next;
}
}
if (pass++ < max_pass)
goto next_pass;
}
void
ipfw_remove_dyn_children(struct ip_fw *rule)
{
IPFW_DYN_LOCK();
remove_dyn_rule(rule, NULL /* force removal */);
IPFW_DYN_UNLOCK();
}
/*
* Lookup a dynamic rule, locked version.
*/
static ipfw_dyn_rule *
lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int *match_direction,
struct tcphdr *tcp)
{
/*
* Stateful ipfw extensions.
* Lookup into dynamic session queue.
*/
#define MATCH_REVERSE 0
#define MATCH_FORWARD 1
#define MATCH_NONE 2
#define MATCH_UNKNOWN 3
int i, dir = MATCH_NONE;
ipfw_dyn_rule *prev, *q = NULL;
IPFW_DYN_LOCK_ASSERT();
if (V_ipfw_dyn_v == NULL)
goto done; /* not found */
i = hash_packet(pkt);
for (prev = NULL, q = V_ipfw_dyn_v[i]; q != NULL;) {
if (q->dyn_type == O_LIMIT_PARENT && q->count)
goto next;
if (TIME_LEQ(q->expire, time_uptime)) { /* expire entry */
UNLINK_DYN_RULE(prev, V_ipfw_dyn_v[i], q);
continue;
}
if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT)
goto next;
if (IS_IP6_FLOW_ID(pkt)) {
if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.src_ip6) &&
IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.dst_ip6) &&
pkt->src_port == q->id.src_port &&
pkt->dst_port == q->id.dst_port) {
dir = MATCH_FORWARD;
break;
}
if (IN6_ARE_ADDR_EQUAL(&pkt->src_ip6, &q->id.dst_ip6) &&
IN6_ARE_ADDR_EQUAL(&pkt->dst_ip6, &q->id.src_ip6) &&
pkt->src_port == q->id.dst_port &&
pkt->dst_port == q->id.src_port) {
dir = MATCH_REVERSE;
break;
}
} else {
if (pkt->src_ip == q->id.src_ip &&
pkt->dst_ip == q->id.dst_ip &&
pkt->src_port == q->id.src_port &&
pkt->dst_port == q->id.dst_port) {
dir = MATCH_FORWARD;
break;
}
if (pkt->src_ip == q->id.dst_ip &&
pkt->dst_ip == q->id.src_ip &&
pkt->src_port == q->id.dst_port &&
pkt->dst_port == q->id.src_port) {
dir = MATCH_REVERSE;
break;
}
}
next:
prev = q;
q = q->next;
}
if (q == NULL)
goto done; /* q = NULL, not found */
if (prev != NULL) { /* found and not in front */
prev->next = q->next;
q->next = V_ipfw_dyn_v[i];
V_ipfw_dyn_v[i] = q;
}
if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
uint32_t ack;
u_char flags = pkt->_flags & (TH_FIN | TH_SYN | TH_RST);
#define BOTH_SYN (TH_SYN | (TH_SYN << 8))
#define BOTH_FIN (TH_FIN | (TH_FIN << 8))
#define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8))
#define ACK_FWD 0x10000 /* fwd ack seen */
#define ACK_REV 0x20000 /* rev ack seen */
q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8);
switch (q->state & TCP_FLAGS) {
case TH_SYN: /* opening */
q->expire = time_uptime + V_dyn_syn_lifetime;
break;
case BOTH_SYN: /* move to established */
case BOTH_SYN | TH_FIN: /* one side tries to close */
case BOTH_SYN | (TH_FIN << 8):
#define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
if (tcp == NULL)
break;
ack = ntohl(tcp->th_ack);
if (dir == MATCH_FORWARD) {
if (q->ack_fwd == 0 ||
_SEQ_GE(ack, q->ack_fwd)) {
q->ack_fwd = ack;
q->state |= ACK_FWD;
}
} else {
if (q->ack_rev == 0 ||
_SEQ_GE(ack, q->ack_rev)) {
q->ack_rev = ack;
q->state |= ACK_REV;
}
}
if ((q->state & (ACK_FWD | ACK_REV)) ==
(ACK_FWD | ACK_REV)) {
q->expire = time_uptime + V_dyn_ack_lifetime;
q->state &= ~(ACK_FWD | ACK_REV);
}
break;
case BOTH_SYN | BOTH_FIN: /* both sides closed */
if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
V_dyn_fin_lifetime = V_dyn_keepalive_period - 1;
q->expire = time_uptime + V_dyn_fin_lifetime;
break;
default:
#if 0
/*
* reset or some invalid combination, but can also
* occur if we use keep-state the wrong way.
*/
if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
printf("invalid state: 0x%x\n", q->state);
#endif
if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
V_dyn_rst_lifetime = V_dyn_keepalive_period - 1;
q->expire = time_uptime + V_dyn_rst_lifetime;
break;
}
} else if (pkt->proto == IPPROTO_UDP) {
q->expire = time_uptime + V_dyn_udp_lifetime;
} else {
/* other protocols */
q->expire = time_uptime + V_dyn_short_lifetime;
}
done:
if (match_direction != NULL)
*match_direction = dir;
return (q);
}
ipfw_dyn_rule *
ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
struct tcphdr *tcp)
{
ipfw_dyn_rule *q;
IPFW_DYN_LOCK();
q = lookup_dyn_rule_locked(pkt, match_direction, tcp);
if (q == NULL)
IPFW_DYN_UNLOCK();
/* NB: return table locked when q is not NULL */
return q;
}
static void
realloc_dynamic_table(void)
{
IPFW_DYN_LOCK_ASSERT();
/*
* Try reallocation, make sure we have a power of 2 and do
* not allow more than 64k entries. In case of overflow,
* default to 1024.
*/
if (V_dyn_buckets > 65536)
V_dyn_buckets = 1024;
if ((V_dyn_buckets & (V_dyn_buckets-1)) != 0) { /* not a power of 2 */
V_dyn_buckets = V_curr_dyn_buckets; /* reset */
return;
}
V_curr_dyn_buckets = V_dyn_buckets;
if (V_ipfw_dyn_v != NULL)
free(V_ipfw_dyn_v, M_IPFW);
for (;;) {
V_ipfw_dyn_v = malloc(V_curr_dyn_buckets * sizeof(ipfw_dyn_rule *),
M_IPFW, M_NOWAIT | M_ZERO);
if (V_ipfw_dyn_v != NULL || V_curr_dyn_buckets <= 2)
break;
V_curr_dyn_buckets /= 2;
}
}
/**
* Install state of type 'type' for a dynamic session.
* The hash table contains two type of rules:
* - regular rules (O_KEEP_STATE)
* - rules for sessions with limited number of sess per user
* (O_LIMIT). When they are created, the parent is
* increased by 1, and decreased on delete. In this case,
* the third parameter is the parent rule and not the chain.
* - "parent" rules for the above (O_LIMIT_PARENT).
*/
static ipfw_dyn_rule *
add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule)
{
ipfw_dyn_rule *r;
int i;
IPFW_DYN_LOCK_ASSERT();
if (V_ipfw_dyn_v == NULL ||
(V_dyn_count == 0 && V_dyn_buckets != V_curr_dyn_buckets)) {
realloc_dynamic_table();
if (V_ipfw_dyn_v == NULL)
return NULL; /* failed ! */
}
i = hash_packet(id);
r = uma_zalloc(ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
if (r == NULL) {
printf ("ipfw: sorry cannot allocate state\n");
return NULL;
}
/* increase refcount on parent, and set pointer */
if (dyn_type == O_LIMIT) {
ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
if ( parent->dyn_type != O_LIMIT_PARENT)
panic("invalid parent");
parent->count++;
r->parent = parent;
rule = parent->rule;
}
r->id = *id;
r->expire = time_uptime + V_dyn_syn_lifetime;
r->rule = rule;
r->dyn_type = dyn_type;
r->pcnt = r->bcnt = 0;
r->count = 0;
r->bucket = i;
r->next = V_ipfw_dyn_v[i];
V_ipfw_dyn_v[i] = r;
V_dyn_count++;
DEB({
struct in_addr da;
#ifdef INET6
char src[INET6_ADDRSTRLEN];
char dst[INET6_ADDRSTRLEN];
#else
char src[INET_ADDRSTRLEN];
char dst[INET_ADDRSTRLEN];
#endif
#ifdef INET6
if (IS_IP6_FLOW_ID(&(r->id))) {
ip6_sprintf(src, &r->id.src_ip6);
ip6_sprintf(dst, &r->id.dst_ip6);
} else
#endif
{
da.s_addr = htonl(r->id.src_ip);
inet_ntoa_r(da, src);
da.s_addr = htonl(r->id.dst_ip);
inet_ntoa_r(da, dst);
}
printf("ipfw: add dyn entry ty %d %s %d -> %s %d, total %d\n",
dyn_type, src, r->id.src_port, dst, r->id.dst_port,
V_dyn_count);
})
return r;
}
/**
* lookup dynamic parent rule using pkt and rule as search keys.
* If the lookup fails, then install one.
*/
static ipfw_dyn_rule *
lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule)
{
ipfw_dyn_rule *q;
int i;
IPFW_DYN_LOCK_ASSERT();
if (V_ipfw_dyn_v) {
int is_v6 = IS_IP6_FLOW_ID(pkt);
i = hash_packet( pkt );
for (q = V_ipfw_dyn_v[i] ; q != NULL ; q=q->next)
if (q->dyn_type == O_LIMIT_PARENT &&
rule== q->rule &&
pkt->proto == q->id.proto &&
pkt->src_port == q->id.src_port &&
pkt->dst_port == q->id.dst_port &&
(
(is_v6 &&
IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
&(q->id.src_ip6)) &&
IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
&(q->id.dst_ip6))) ||
(!is_v6 &&
pkt->src_ip == q->id.src_ip &&
pkt->dst_ip == q->id.dst_ip)
)
) {
q->expire = time_uptime + V_dyn_short_lifetime;
DEB(printf("ipfw: lookup_dyn_parent found 0x%p\n",q);)
return q;
}
}
return add_dyn_rule(pkt, O_LIMIT_PARENT, rule);
}
/**
* Install dynamic state for rule type cmd->o.opcode
*
* Returns 1 (failure) if state is not installed because of errors or because
* session limitations are enforced.
*/
int
ipfw_install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
struct ip_fw_args *args, uint32_t tablearg)
{
static int last_log;
ipfw_dyn_rule *q;
struct in_addr da;
#ifdef INET6
char src[INET6_ADDRSTRLEN + 2], dst[INET6_ADDRSTRLEN + 2];
#else
char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
#endif
src[0] = '\0';
dst[0] = '\0';
IPFW_DYN_LOCK();
DEB(
#ifdef INET6
if (IS_IP6_FLOW_ID(&(args->f_id))) {
ip6_sprintf(src, &args->f_id.src_ip6);
ip6_sprintf(dst, &args->f_id.dst_ip6);
} else
#endif
{
da.s_addr = htonl(args->f_id.src_ip);
inet_ntoa_r(da, src);
da.s_addr = htonl(args->f_id.dst_ip);
inet_ntoa_r(da, dst);
}
printf("ipfw: %s: type %d %s %u -> %s %u\n",
__func__, cmd->o.opcode, src, args->f_id.src_port,
dst, args->f_id.dst_port);
src[0] = '\0';
dst[0] = '\0';
)
q = lookup_dyn_rule_locked(&args->f_id, NULL, NULL);
if (q != NULL) { /* should never occur */
DEB(
if (last_log != time_uptime) {
last_log = time_uptime;
printf("ipfw: %s: entry already present, done\n",
__func__);
})
IPFW_DYN_UNLOCK();
return (0);
}
if (V_dyn_count >= V_dyn_max)
/* Run out of slots, try to remove any expired rule. */
remove_dyn_rule(NULL, (ipfw_dyn_rule *)1);
if (V_dyn_count >= V_dyn_max) {
if (last_log != time_uptime) {
last_log = time_uptime;
printf("ipfw: %s: Too many dynamic rules\n", __func__);
}
IPFW_DYN_UNLOCK();
return (1); /* cannot install, notify caller */
}
switch (cmd->o.opcode) {
case O_KEEP_STATE: /* bidir rule */
add_dyn_rule(&args->f_id, O_KEEP_STATE, rule);
break;
case O_LIMIT: { /* limit number of sessions */
struct ipfw_flow_id id;
ipfw_dyn_rule *parent;
uint32_t conn_limit;
uint16_t limit_mask = cmd->limit_mask;
conn_limit = (cmd->conn_limit == IP_FW_TABLEARG) ?
tablearg : cmd->conn_limit;
DEB(
if (cmd->conn_limit == IP_FW_TABLEARG)
printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
"(tablearg)\n", __func__, conn_limit);
else
printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
__func__, conn_limit);
)
id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
id.proto = args->f_id.proto;
id.addr_type = args->f_id.addr_type;
id.fib = M_GETFIB(args->m);
if (IS_IP6_FLOW_ID (&(args->f_id))) {
if (limit_mask & DYN_SRC_ADDR)
id.src_ip6 = args->f_id.src_ip6;
if (limit_mask & DYN_DST_ADDR)
id.dst_ip6 = args->f_id.dst_ip6;
} else {
if (limit_mask & DYN_SRC_ADDR)
id.src_ip = args->f_id.src_ip;
if (limit_mask & DYN_DST_ADDR)
id.dst_ip = args->f_id.dst_ip;
}
if (limit_mask & DYN_SRC_PORT)
id.src_port = args->f_id.src_port;
if (limit_mask & DYN_DST_PORT)
id.dst_port = args->f_id.dst_port;
if ((parent = lookup_dyn_parent(&id, rule)) == NULL) {
printf("ipfw: %s: add parent failed\n", __func__);
IPFW_DYN_UNLOCK();
return (1);
}
if (parent->count >= conn_limit) {
/* See if we can remove some expired rule. */
remove_dyn_rule(rule, parent);
if (parent->count >= conn_limit) {
if (V_fw_verbose && last_log != time_uptime) {
last_log = time_uptime;
#ifdef INET6
/*
* XXX IPv6 flows are not
* supported yet.
*/
if (IS_IP6_FLOW_ID(&(args->f_id))) {
char ip6buf[INET6_ADDRSTRLEN];
snprintf(src, sizeof(src),
"[%s]", ip6_sprintf(ip6buf,
&args->f_id.src_ip6));
snprintf(dst, sizeof(dst),
"[%s]", ip6_sprintf(ip6buf,
&args->f_id.dst_ip6));
} else
#endif
{
da.s_addr =
htonl(args->f_id.src_ip);
inet_ntoa_r(da, src);
da.s_addr =
htonl(args->f_id.dst_ip);
inet_ntoa_r(da, dst);
}
log(LOG_SECURITY | LOG_DEBUG,
"ipfw: %d %s %s:%u -> %s:%u, %s\n",
parent->rule->rulenum,
"drop session",
src, (args->f_id.src_port),
dst, (args->f_id.dst_port),
"too many entries");
}
IPFW_DYN_UNLOCK();
return (1);
}
}
add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent);
break;
}
default:
printf("ipfw: %s: unknown dynamic rule type %u\n",
__func__, cmd->o.opcode);
IPFW_DYN_UNLOCK();
return (1);
}
/* XXX just set lifetime */
lookup_dyn_rule_locked(&args->f_id, NULL, NULL);
IPFW_DYN_UNLOCK();
return (0);
}
/*
* Generate a TCP packet, containing either a RST or a keepalive.
* When flags & TH_RST, we are sending a RST packet, because of a
* "reset" action matched the packet.
* Otherwise we are sending a keepalive, and flags & TH_
* The 'replyto' mbuf is the mbuf being replied to, if any, and is required
* so that MAC can label the reply appropriately.
*/
struct mbuf *
ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
u_int32_t ack, int flags)
{
struct mbuf *m = NULL; /* stupid compiler */
int len, dir;
struct ip *h = NULL; /* stupid compiler */
#ifdef INET6
struct ip6_hdr *h6 = NULL;
#endif
struct tcphdr *th = NULL;
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m == NULL)
return (NULL);
M_SETFIB(m, id->fib);
#ifdef MAC
if (replyto != NULL)
mac_netinet_firewall_reply(replyto, m);
else
mac_netinet_firewall_send(m);
#else
(void)replyto; /* don't warn about unused arg */
#endif
switch (id->addr_type) {
case 4:
len = sizeof(struct ip) + sizeof(struct tcphdr);
break;
#ifdef INET6
case 6:
len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
break;
#endif
default:
/* XXX: log me?!? */
FREE_PKT(m);
return (NULL);
}
dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN);
m->m_data += max_linkhdr;
m->m_flags |= M_SKIP_FIREWALL;
m->m_pkthdr.len = m->m_len = len;
m->m_pkthdr.rcvif = NULL;
bzero(m->m_data, len);
switch (id->addr_type) {
case 4:
h = mtod(m, struct ip *);
/* prepare for checksum */
h->ip_p = IPPROTO_TCP;
h->ip_len = htons(sizeof(struct tcphdr));
if (dir) {
h->ip_src.s_addr = htonl(id->src_ip);
h->ip_dst.s_addr = htonl(id->dst_ip);
} else {
h->ip_src.s_addr = htonl(id->dst_ip);
h->ip_dst.s_addr = htonl(id->src_ip);
}
th = (struct tcphdr *)(h + 1);
break;
#ifdef INET6
case 6:
h6 = mtod(m, struct ip6_hdr *);
/* prepare for checksum */
h6->ip6_nxt = IPPROTO_TCP;
h6->ip6_plen = htons(sizeof(struct tcphdr));
if (dir) {
h6->ip6_src = id->src_ip6;
h6->ip6_dst = id->dst_ip6;
} else {
h6->ip6_src = id->dst_ip6;
h6->ip6_dst = id->src_ip6;
}
th = (struct tcphdr *)(h6 + 1);
break;
#endif
}
if (dir) {
th->th_sport = htons(id->src_port);
th->th_dport = htons(id->dst_port);
} else {
th->th_sport = htons(id->dst_port);
th->th_dport = htons(id->src_port);
}
th->th_off = sizeof(struct tcphdr) >> 2;
if (flags & TH_RST) {
if (flags & TH_ACK) {
th->th_seq = htonl(ack);
th->th_flags = TH_RST;
} else {
if (flags & TH_SYN)
seq++;
th->th_ack = htonl(seq);
th->th_flags = TH_RST | TH_ACK;
}
} else {
/*
* Keepalive - use caller provided sequence numbers
*/
th->th_seq = htonl(seq);
th->th_ack = htonl(ack);
th->th_flags = TH_ACK;
}
switch (id->addr_type) {
case 4:
th->th_sum = in_cksum(m, len);
/* finish the ip header */
h->ip_v = 4;
h->ip_hl = sizeof(*h) >> 2;
h->ip_tos = IPTOS_LOWDELAY;
h->ip_off = 0;
/* ip_len must be in host format for ip_output */
h->ip_len = len;
h->ip_ttl = V_ip_defttl;
h->ip_sum = 0;
break;
#ifdef INET6
case 6:
th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6),
sizeof(struct tcphdr));
/* finish the ip6 header */
h6->ip6_vfc |= IPV6_VERSION;
h6->ip6_hlim = IPV6_DEFHLIM;
break;
#endif
}
return (m);
}
/*
* This procedure is only used to handle keepalives. It is invoked
* every dyn_keepalive_period
*/
static void
ipfw_tick(void * vnetx)
{
struct mbuf *m0, *m, *mnext, **mtailp;
#ifdef INET6
struct mbuf *m6, **m6_tailp;
#endif
int i;
ipfw_dyn_rule *q;
#ifdef VIMAGE
struct vnet *vp = vnetx;
#endif
CURVNET_SET(vp);
if (V_dyn_keepalive == 0 || V_ipfw_dyn_v == NULL || V_dyn_count == 0)
goto done;
/*
* We make a chain of packets to go out here -- not deferring
* until after we drop the IPFW dynamic rule lock would result
* in a lock order reversal with the normal packet input -> ipfw
* call stack.
*/
m0 = NULL;
mtailp = &m0;
#ifdef INET6
m6 = NULL;
m6_tailp = &m6;
#endif
IPFW_DYN_LOCK();
for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
for (q = V_ipfw_dyn_v[i] ; q ; q = q->next ) {
if (q->dyn_type == O_LIMIT_PARENT)
continue;
if (q->id.proto != IPPROTO_TCP)
continue;
if ( (q->state & BOTH_SYN) != BOTH_SYN)
continue;
if (TIME_LEQ(time_uptime + V_dyn_keepalive_interval,
q->expire))
continue; /* too early */
if (TIME_LEQ(q->expire, time_uptime))
continue; /* too late, rule expired */
m = (q->state & ACK_REV) ? NULL :
ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1,
q->ack_fwd, TH_SYN);
mnext = (q->state & ACK_FWD) ? NULL :
ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1,
q->ack_rev, 0);
switch (q->id.addr_type) {
case 4:
if (m != NULL) {
*mtailp = m;
mtailp = &(*mtailp)->m_nextpkt;
}
if (mnext != NULL) {
*mtailp = mnext;
mtailp = &(*mtailp)->m_nextpkt;
}
break;
#ifdef INET6
case 6:
if (m != NULL) {
*m6_tailp = m;
m6_tailp = &(*m6_tailp)->m_nextpkt;
}
if (mnext != NULL) {
*m6_tailp = mnext;
m6_tailp = &(*m6_tailp)->m_nextpkt;
}
break;
#endif
}
}
}
IPFW_DYN_UNLOCK();
for (m = m0; m != NULL; m = mnext) {
mnext = m->m_nextpkt;
m->m_nextpkt = NULL;
ip_output(m, NULL, NULL, 0, NULL, NULL);
}
#ifdef INET6
for (m = m6; m != NULL; m = mnext) {
mnext = m->m_nextpkt;
m->m_nextpkt = NULL;
ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
}
#endif
done:
callout_reset_on(&V_ipfw_timeout, V_dyn_keepalive_period * hz,
ipfw_tick, vnetx, 0);
CURVNET_RESTORE();
}
void
ipfw_dyn_attach(void)
{
ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, 0);
IPFW_DYN_LOCK_INIT();
}
void
ipfw_dyn_detach(void)
{
uma_zdestroy(ipfw_dyn_rule_zone);
IPFW_DYN_LOCK_DESTROY();
}
void
ipfw_dyn_init(void)
{
V_ipfw_dyn_v = NULL;
V_dyn_buckets = 256; /* must be power of 2 */
V_curr_dyn_buckets = 256; /* must be power of 2 */
V_dyn_ack_lifetime = 300;
V_dyn_syn_lifetime = 20;
V_dyn_fin_lifetime = 1;
V_dyn_rst_lifetime = 1;
V_dyn_udp_lifetime = 10;
V_dyn_short_lifetime = 5;
V_dyn_keepalive_interval = 20;
V_dyn_keepalive_period = 5;
V_dyn_keepalive = 1; /* do send keepalives */
V_dyn_max = 4096; /* max # of dynamic rules */
callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE);
callout_reset_on(&V_ipfw_timeout, hz, ipfw_tick, curvnet, 0);
}
void
ipfw_dyn_uninit(int pass)
{
if (pass == 0)
callout_drain(&V_ipfw_timeout);
else {
if (V_ipfw_dyn_v != NULL)
free(V_ipfw_dyn_v, M_IPFW);
}
}
int
ipfw_dyn_len(void)
{
return (V_ipfw_dyn_v == NULL) ? 0 :
(V_dyn_count * sizeof(ipfw_dyn_rule));
}
void
ipfw_get_dynamic(char **pbp, const char *ep)
{
ipfw_dyn_rule *p, *last = NULL;
char *bp;
int i;
if (V_ipfw_dyn_v == NULL)
return;
bp = *pbp;
IPFW_DYN_LOCK();
for (i = 0 ; i < V_curr_dyn_buckets; i++)
for (p = V_ipfw_dyn_v[i] ; p != NULL; p = p->next) {
if (bp + sizeof *p <= ep) {
ipfw_dyn_rule *dst =
(ipfw_dyn_rule *)bp;
bcopy(p, dst, sizeof *p);
bcopy(&(p->rule->rulenum), &(dst->rule),
sizeof(p->rule->rulenum));
/*
* store set number into high word of
* dst->rule pointer.
*/
bcopy(&(p->rule->set),
(char *)&dst->rule +
sizeof(p->rule->rulenum),
sizeof(p->rule->set));
/*
* store a non-null value in "next".
* The userland code will interpret a
* NULL here as a marker
* for the last dynamic rule.
*/
bcopy(&dst, &dst->next, sizeof(dst));
last = dst;
dst->expire =
TIME_LEQ(dst->expire, time_uptime) ?
0 : dst->expire - time_uptime ;
bp += sizeof(ipfw_dyn_rule);
}
}
IPFW_DYN_UNLOCK();
if (last != NULL) /* mark last dynamic rule */
bzero(&last->next, sizeof(last));
*pbp = bp;
}
/* end of file */